The present invention relates generally to the field of medical diagnostics and more specifically to a non-invasive temperature monitor for a sleeping patient.
One of the most important medical diagnostic tools in a doctors arsenal is the monitoring of a patient""s temperature. When a patient has a temperature above normal, it is an indication to the doctor that there is something medically wrong with the patient. This important illness indicator will tell the doctor he should make further inquiries and/or do further tests to determine what exactly the problem is with the patient.
Taking the temperature of a patient is usually done orally or anally when the patient is awake. A conventional mercury or iodine filled glass thermometer is well suited for such temperature taking methods. Recently, an electronic thermometer has been introduced that takes the patient""s temperature by inserting a short tubular piece attached to the thermometer into the patient""s ear for several seconds. This hand held electronic thermometer shortens the required time period that the thermometer must be held in place before an accurate temperature may calculated. However, the hand held electronic thermometer shares similar disadvantages as those of the conventional glass thermometers. Each of the above methods of taking temperature is semi-invasive and a doctor, nurse or other person usually must handle or otherwise assist in the taking and monitoring of the patient""s temperature. Even though it is possible for a patient to take their own temperature, this requires the patient to be awake and have access to and knowledge of the thermometer that is used.
These traditional methods of taking a temperature do not provide for automatic monitoring of the patient""s temperature while the patient is sleeping. Each method requires a doctor or nurse or the patient himself to administer the temperature test at night when the patient would normally be asleep. The above conventional methods require multiple tests that must be repeated in short intervals to provide continuous monitoring of the patient""s temperature.
Continuous temperature monitoring is necessary to detect illnesses as early as possible in patient""s that are immuno-compromised or are susceptible to recurrent febrile (fever related) illnesses. Patients with an immune system that for some reason or another is not operating normally is said to be immuno-compromised. These patient""s must prevent illnesses because their bodies no longer have their full ability to fight back against illnesses. Since a fever is usually one of the first symptoms of an oncoming illness, automated nighttime monitoring provides a great benefit to these patient""s. Continuous night time temperature monitoring is also desirable for young children, especially those that suffer from febrile illnesses that could lead to febrile convulsions. Febrile convulsions occur in almost 2% of children below six years of age. The current state of the art for prophylaxis is to prevent recurrence of febrile convulsions which means preventing the precipitating fever or to use prophylactic oral diazepam during the febrile episode (1). Some children may even seize with only a minimal elevation in temperature, before the parent recognizes the symptoms of a fever. Further, children who suffer from febrile convulsions do not respond well to anticonvulsive drugs, which unfortunately can also cause serious side effects. Therefore, early detection of an oncoming fever is quite desirable and could also save the child""s life
Sometimes, a mild fever is overlooked by parent in the morning and few hours later the school or the day care calls and informs the family that their child is sick and the family needs to come and pick up the child.
Sleep represents one third of the life of children and most adults. Some children sleep 8-10 hours a day. During the day, children are observed and symptoms of a fever are more likely to be noticed than during the night time. The present invention monitors the temperature non-invasively during the night time in a way that allows it to be used on a daily basis, all year long. In an alternative embodiment, a parent can use a receiver/microphone to receive a temperature alarm (buzzing) transmission from the monitor.
Another method to measure the body temperature was a plastic strip thermometer that had to be affixed to the patient""s forehead. This method brought about conflicting results. In one clinical trial published in JAMA (2), its accuracy was affected by variations in ambient air temperature. The conclusion of this study was that the method is unacceptable as a substitute for the mercury/glass thermometer. The medical consensus is that the forehead temperature is not as accurate as the other mode of temperature taking (i.e., rectal, oral, axially and aural). None of the traditional temperature taking methods mentioned above provide long term continuous non-invasive automated monitoring of a patient""s temperature. What is needed is a non-invasive method for monitoring of a patient""s temperature so that monitoring can automatically take place when the patient is asleep or napping.
The present invention solves the above problem by providing one or more temperature sensors that are attached to a patient""s pillow or pillowcase. The human head has a rich blood supply and human hair is not a significant insulator of heat. This allows accurate temperature taking from a patient""s head. A wire attaches the sensor to a temperature monitor. The monitor reads and stores the patient""s temperature and sounds an alarm when the patient""s temperature rises above a preset temperature, such as 98.5 F. The monitor can be placed in the patient""s room or it can be located in another room. In the case where a child is the xe2x80x9cpatientxe2x80x9d, the monitor can advantageously be place in the parent""s room. In this way, the parent would be alerted immediately when the child""s temperature begins to rise above normal. The parent could then take defensive actions to try to bring down the child""s temperature, such as cold sponges, removal of heavy clothing, antipyretics and possibly antibiotics. In the traditional temperature taking methods, the parent would not know of a fever that developed overnight in their child until the morning. This late diagnosis of a fever could be detrimental to children that suffer from febrile convulsions.
Metallic temperature sensors provide accurate temperature calculations based on the dynamic resistive properties of the metal. As the temperature of the metal changes, the resistivity of the metal changes. When a small electrical current is sent to the metal, the resistance of the metal can be calculated based on the current that comes out of the metal. Resistance values are matched to temperature values dependant upon the type of metal that is used in the thermometer. Platinum is known as an extremely accurate metal for use in electrical resistance thermometers. However, other metals such as copper, stainless steel and nickel are suitable substitutes.
In the preferred embodiment, one or more thin pieces of metal that act as electrical resistance thermometers are attached to a pillow or pillowcase that a patient will use to rest her head on. The metallic thermometer(s) are electrically connected to a monitor unit that has a display and memory. The monitor unit selectively displays current temperature or past temperatures with corresponding times. The monitor unit also has an alarm that sounds when the patient""s temperature rises above a preset value. The present invention may be used when the patient goes to bed at night and in many cases the patient may be a young child and the person listening for the alarm may be the child""s parent.